The present application claims priority under 35 U.S.C. xc2xa7119 of Austrian Patent Application No. 1442/2001, filed Sep. 13, 2001.
1. Field of the Invention
The invention relates to a device for the hardening of rolling stock having a large lengthwise extension at a high throughput. More precisely defined, the invention relates to a device for the thermal tempering of at least portions of the cross section over the lengthwise extension of sequentially produced profiled rolling stock from the rolling heat, in particular for hardening at least the head of rails having a length greater than 50 m, and subsequent cooling to room temperature, consisting essentially of a roller table, a means for arranging the rolling stock in axial alignment, a transport means having a rest for the rolling stock for the transport thereof in transverse direction, a hardening device with a manipulation arrangement, and a cooling bed.
2. Discussion of Background Information
In order to improve the properties of the material, a rolling stock is usually subjected to a thermal tempering treatment that advantageously is carried out with the use of the rolling heat. This tempering, which essentially affords an increase in the mechanical properties of the material such as hardness, abrasion resistance, and the like, can be performed over the entire cross section or, as is common with a running rail, only over partial sections of the same. Here, the rolling stock which is in its austenitic microstructural state, or partial sections of the cross section of the same, is dipped into a cooling medium over its entire length and, in this manner, a transformation of the microstructure is achieved in the desired manner.
Devices for carrying out such tempering processes are known (EP-0441766 B1) and have proven suitable with regard to an improvement of the use properties of railroad rails.
Depending on the final rolling temperature and depending on the specific mass or mass per length unit, respectively, of the rolling stock, thermal tempering thereof requires a corresponding submersion time or residence time in the cooling liquid, such that the throughput through the tempering device is limited. In other words, the maximum possible throughput through a submersion tempering installation with a cooling basin limits the output of the rolling device arranged before it.
Modern roll-forming lines with prearranged heating furnaces particularly for continuous casting input stock usually have potential rolling outputs that are greater than the throughput of known submersion tempering installations, so that with a sequential production of hardened rails, the rolling output has to be reduced.
In order to avoid this disadvantage, which is in particular an economic one, it has already been recommended to temper the rolling stock as it moves through a cooling path provided with spraying means. However, this continuous pass process requires long lengths of the installation and usually does not result in the required material quality of the rolling stock.
The invention aims at avoiding the deficiencies and, in particular, the economic disadvantages, of known thermal treatment installations for rolling stock of the type mentioned at the outset and at providing a device that ensures a high quality and good use properties of the rolling stock produced and has a high output and renders possible the treatment and thermal tempering of sequentially produced bar stock, particularly of rails having lengths of more than 50 m, on roll lines with high output while using rolling heat.
This goal is attained in a generic device in that the roller table has a device for longitudinally positioning the rolling stock which is supplied supported in at least one cross-sectional region, and an assigned alignment means, in that the hardening device is formed of at least two liquid cooling devices arranged next to one another essentially parallel in their lengthwise direction to the alignment means with manipulators for a movement of the rolling stock, in that the deposit region of the cooling bed is located next to, and parallel to the lengthwise extension of, the liquid cooling devices, and in that the means for transport in transverse direction has at least two supporting arms that are simultaneously movable between the roller table rolls, each having rolling stock rests arranged on the end side, that these rests on the supporting arms can be moved in transverse direction from the alignment position in the region of the roller table into the deposit region of the cooling bed, lowered, and raised in such a way that exclusively the rests protrude beyond the transport surface of the roller table and the upper edge of the roller table, respectively.
The present invention provides a device for tempering at least parts of the cross section of sequentially produced profiled rolling stock from the rolling heat and for the subsequent cooling thereof to room temperature. This device consists essentially of (a) a roller table that comprises rolls and receives said rolling stock, (b) an alignment device for axially aligning the rolling stock, (c) a transport device for transporting the rolling stock in transverse direction, (d) a hardening device for hardening the rolling stock which comprises a manipulator arrangement for manipulating the rolling stock to be hardened, and (e) a cooling bed for the hardened rolling stock, said cooling bed comprising a deposit region. The roller table (a) further comprises a positioning device for positioning in longitudinal direction the rolling stock which is supplied thereto, which positioning device comprises said alignment device (b). The transport device (c) comprises at least two supporting arms that are simultaneously movable between the rolls of the roller table. Each of these arms, in turn, comprises at an end section thereof a rest for supporting said rolling stock. The rests on the supporting arms can be moved in transverse direction from an alignment position in the region of the roller table into the deposit region of the cooling bed (e) and can be raised in such a way that only the rests are above an upper surface of the roller table. The hardening device (d) comprises at least two liquid cooling devices and manipulators for moving the rolling stock. These liquid cooling devices are arranged next to one another and essentially parallel to the alignment device (b). Furthermore, the deposit region of the cooling bed is arranged next to and parallel to the lengthwise extension of the liquid cooling devices.
In one aspect of the device, the rolling stock is a rail, e.g., a rail having a length of greater than 50 m. This rail may, for example, be a running rail or a railroad rail. In another aspect, at least the head of the rail is hardened. In yet another aspect, the roller table can support the rail in two cross-sectional regions thereof.
According to another aspect of the device, the positioning device comprises an electronically controllable device and/or an alignment bar and/or a stop.
According to still another aspect, the liquid cooling devices comprise submersion basins. These submersion basins may comprise stops for leveling and aligning the rolling stock. The stops may be arranged, for example, horizontally and/or vertically. In another aspect, a holding-down device for pressing down the rolling stock against said stops may additionally be provided.
According to a further aspect, each submersion basin has manipulators assigned to it. Each of said manipulators may be capable of, e.g., taking the rolling stock off the rests of the transport device (c), introducing the rolling stock into a submersion basin, lifting the rolling stock out of a submersion basin, and/or placing the rolling stock back on said rests. Moreover, said manipulators may be capable of introducing a rail xe2x80x9chead downxe2x80x9d into a submersion basin.
According to yet another aspect of the device, each of said supporting arms has exactly one rest arranged thereon. In another aspect, the supporting arms originate in the region of the roller table. Alternatively, the transport device (c) may be arranged in the region of the cooling bed.
The present invention also provides a process for tempering at least parts of the cross section of sequentially produced profiled rolling stock from the rolling heat and for subsequently cooling said rolling stock to room temperature. This process comprises axially aligning said rolling stock, transporting the rolling stock to a hardening device and treating at least parts of the cross section of the rolling stock therewith, and allowing the rolling stock so treated with the hardening device to cool to room temperature. In this process, the residence time in the hardening device exceeds the supply frequency of the rolling stock to be tempered and the process is carried out by means of a device as described above.
The advantages attained by the invention lie especially in the fact that, using the device, it is possible to position and axially align the rolling stock in a simple manner in sequence in the transverse transport region of the roller table with a high degree of precision, it being possible, by means of the rolling stock rests of the means for transport in transverse direction, to simultaneously, i.e., without interfering with the adjustment and the axial alignment process, transport a previously aligned and provided piece of rolling stock into the deposit regions of the cooling devices or from there into the deposit region of the cooling bed or from the roller table directly onto the cooling bed. In this connection, it is important that only the rolling stock rests of the supporting arms of the means for transport in transverse direction, which arms are movable between the rolls, are capable of being raised above the upper level of the rolls of the roller table or their transport surface, respectively. With this embodiment of the device, it is possible to arrange at least two hardening devices on one side of the roller table such that a cooling bed must be provided on one side only, which yields economic advantages. A piece of rolling stock that is positioned on the roller table and axially aligned can be lifted off the roller table by means of the rests of the supporting arms and, for example, be laid down in a deposit region of a liquid cooling device that is embodied as a manipulator. Thereafter the means for transport in transverse direction is freed up for transporting further pieces of rolling stock, where the manipulator can, alone and independently, orient the deposited rolling stock in its cross-sectional position, place it in the cooling medium at least partially, lift it out, and provide it for transport to the cooling bed. This separation of the transport in transverse direction of the rolling stock, which is essential to the invention, even past occupied cooling devices with, eventually, a deposit on the cooling bed, and a precise placement of the rolling stock in the cooling medium improves the precision of the manipulation as well as of the cooling treatment and reliably affords hardened rolled products with consistently high quality. In an advantageous and economical manner, the output and throughput, respectively, of the device is approximately doubled when using two hardening devices next to one another.
If the device is intended for a rolling stock in the form of a running rail or a railroad rail that rests on the roller table in two cross-sectional regions and the positioning device is embodied as an electronically controllable means and/or has an alignment bar or a lateral stop, it is possible in a favorable fashion for the residence time of the rails on the roller table to be reduced, for the temperature control to be improved, and, optionally, for the output of the installation to be increased. Moreover, this position is particularly well suited for a so-called xe2x80x9chead downxe2x80x9d vertical positioning of the rail by means of the manipulators.
If, as may be provided in one embodiment of the invention, the liquid cooling devices are formed as submersion basins that have horizontally and vertically oriented stops acting on the bottom and, optionally, laterally for leveling and aligning the rolling stock, it is possible, in particular in the case of the cooling of parts of the cross section of a rail, for a highly consistent cooling and distribution of hardness to be achieved over its length, which helps to ensure the quality of the product.
It is advantageous for consistent and good use properties if holding-down means for the rolling stock, in particular for a rail, are provided in the device, with which means the rolling stock/rail can be pressed down against the leveling stops in the submersion basin during cooling because this can effectively prevent a bending caused by the cooling and keep the respective local cooling of the surface completely constant.
Particular economic advantages are provided by using the device described above for hardening at least the head of rails having a length of greater than 50 m and subsequent cooling to room temperature at a pass-through time of a rail through the hardening device that exceeds the supply frequency because large increases in performance are possible at comparably low investment costs.